Multi-position rotary switches are used in the low-voltage range for switching large currents in a range of up to 180 amps. The contact force must be dimensioned according to the high current, which requires, in turn, robust housings and activation devices.
The number of required switch contacts is dictated by how many circuits are to be interrupted on the side of the user. As a rule, the number of circuits to be switched starts at three and has an open upper limit. A reasonable upper limit is 6 circuits.
It is understood that the user would not want to use a multi-position rotary switch designed for the maximum number for switching a device with fewer circuits than the maximum possible circuits within the capability of the multi-position rotary switch. Accordingly, the manufacturer of the multi-position rotary switch must provide a spectrum of different multi-position rotary switches that differ with respect to the switchable circuits but not with respect to the electrical criteria. This produces a need for multi-position rotary switches that are constructed in a modular manner by the manufacturer.
Multi-position rotary switches with a modular construction are known that are built as tiers. For activation, a switch shaft is provided that leads centrally through all of the tiers and activates switch push-rods in the individual switch chambers by means of cams. The contact tabs that connect the contacts contained in the switch chambers to the outer wiring extend from the multi-position rotary switch in a star shape accordingly. They also are located at different heights, resulting in a number of disadvantages for the user.
It is difficult to create a reasonable contact protection device for such connection tabs that project in the radial direction, since the protection device may not obstruct accessibility with tools. The connection tabs further are located at different heights, which also makes the configuration of the connection tabs difficult during the installation.
The length of such multi-position rotary switch, viewed in the direction parallel to the switch shaft, changes with the number of cam assemblies, so that the installation depth varies greatly, which require that spaces of different depths be kept available for the multi-position rotary switch.
The combination of star-shaped-projecting connection tabs and different spatial depths further does not contribute to an open arrangement and makes error-free wiring more difficult. Different structural depths have an especially disruptive effect primarily because multi-position rotary switches typically represent relatively large objects that are often are mounted on their back side, if the front side is considered to be the side on which the activation element to be activated manually sits.